feat(fingerprint): password OR fingerprint in parallel at one prompt

Bernardo promoted the PROPOSED item live: with fingerprint PAM on, sudo/login should accept whichever factor comes first instead of pam_fprintd's wait-for-the-reader-then-password. Stock PAM cannot express parallel factors (linux-pam#301), so this packages pam-fprint-grosshack v0.3.0 (pkgs/, pinned from GitLab — the field-standard fprintd fork), source-reviewed before packaging: every failure path (no reader, no prints, fprintd absent/hung, timeout, password typed) returns PAM_AUTHINFO_UNAVAIL and falls through; a typed password is only ferried via PAM_AUTHTOK to the stock `auth sufficient pam_unix.so … try_first_pass` rule — the module never validates passwords itself, so it cannot lock out password login. New option nomarchy.hardware.fingerprint.parallel, default TRUE (the better UX is what opting into fingerprint PAM buys; false = stock sequential). Wiring swaps the modulePath of stock fprintd's rule slot (mkForce) so the sufficient-before-pam_unix ordering is inherited, not recomputed. README + downstream template rows added. Verified: V2 — checks.hardware-toggles extended to three nodes, green: parallel node asserts the grosshack auth line precedes pam_unix in /etc/pam.d/sudo and that with NO reader a correct password still passes sudo while a wrong one fails (the lockout-safety invariant); seqpam node gets stock pam_fprintd and no grosshack; nopam gets neither. flake check + option-docs + template-sot green. V3 pending (HARDWARE-QUEUE, AMD dev box): the real type-or-touch race, fprintd-stopped fallback, hyprlock/greeter after a fingerprint win. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-12 19:03:56 +01:00
parent c840202018
commit 7aae204014
9 changed files with 175 additions and 14 deletions
--- a/README.md
+++ b/README.md
@@ -297,6 +297,7 @@ option, e.g. `services.easyeffects.enable = lib.mkForce false;` — see
 | `nomarchy.hardware.amd.rocm.enable` | `false` | Opt-in: ROCm HIP/OpenCL GPU compute (multi-GB); pair with `.gfxOverride` (e.g. `"11.0.0"`) for an unlisted iGPU |
 | `nomarchy.hardware.fingerprint.enable` | `false` | fprintd for a detected fingerprint reader (installer-set); enroll with `fprintd-enroll` |
 | `nomarchy.hardware.fingerprint.pam` | `false` | Opt-in: use the fingerprint for login + sudo (PAM) |
+| `nomarchy.hardware.fingerprint.parallel` | `true` | With PAM on: password *or* fingerprint at the same prompt (whichever comes first); `false` = stock sequential pam_fprintd. Password alone always stays sufficient |
 | `nomarchy.hardware.npu.enable` | `false` | Opt-in/experimental: load the on-die NPU driver (`amdxdna`/`intel_vpu`); userspace runtime is BYO |
 | `nomarchy.hardware.latestKernel` | `false` | Opt-in: ship `linuxPackages_latest` instead of the default kernel — for very new hardware whose drivers landed recently |
 | `nomarchy.hardware.camera.hideIrSensor` | `false` | Hide a dual-sensor webcam's IR node from PipeWire's **v4l2** path so apps only ever see the colour camera (the "second, dark Integrated Camera"); installer-set on a paired RGB+IR webcam. `/dev/video*` stays open, so Howdy-style face unlock still works; `.irMatch` overrides the IR-name regex. Does **not** hide IR from libcamera / portal / Flatpak pickers — see [HARDWARE.md §7](docs/HARDWARE.md) |
--- a/agent/BACKLOG.md
+++ b/agent/BACKLOG.md
@@ -134,18 +134,11 @@ high-ROI, etc.) live in the journal + ROADMAP — not here.*
  fixture. Control-center / MOTD already mention these; the gap is the
  silent first *graphical* session for people who never open those.

- **Fingerprint *or* password, in parallel** (2026-07-11, Bernardo) —
-  `fingerprint.pam` gives pam_fprintd's sequential UX: sudo waits on
-  the reader, password only after failure/timeout. Bernardo wants
-  either factor accepted at the same prompt (type the password *or*
-  touch the sensor, whichever comes first). Stock PAM can't express
-  this; needs a parallel-conversation module (e.g. `pam-any`, not in
-  nixpkgs — would be a new package + `fingerprint.pam = "any"` mode).
-  Cost: medium (package + PAM wiring + careful lockout testing on real
-  hardware). Security note: keep sudo fallback sane if fprintd hangs.
-
 _(#80–#83 + #85–#88 shipped 2026-07-11. Theme A day-2 + neon-glass finish
-  shipped — VISION ✓. Dock/hibernate V3 → HARDWARE-QUEUE.)_
+  shipped — VISION ✓. Dock/hibernate V3 → HARDWARE-QUEUE. Parallel
+  fingerprint-or-password shipped 2026-07-12 (Bernardo promoted it live;
+  `fingerprint.parallel`, pam-fprint-grosshack) — reader V3 →
+  HARDWARE-QUEUE.)_

 ### v1.0 pointer

--- a/agent/HARDWARE-QUEUE.md
+++ b/agent/HARDWARE-QUEUE.md
@@ -59,6 +59,19 @@ the **T14s** (webcam case).
      the re-lit panel. If that happens on hardware, the "Laptop screen
      off" row needs a rework (mirror instead of disable, or drop until
      a Hyprland bump) — file it as a NOW bug with the coredump.
+- [ ] **Parallel fingerprint-or-password on the real reader** (AMD dev
+      box, 2026-07-12) — with a finger enrolled and
+      `fingerprint.pam = true` (parallel is the default): `sudo -k true`
+      must show ONE prompt ("Enter Password or Place finger…"); typing
+      the password immediately works, touching the sensor instead works,
+      wrong-finger ×3 falls back to password, and password keeps working
+      with fprintd stopped (`systemctl stop fprintd`). Also check
+      hyprlock and the greeter accept both factors and don't wedge on a
+      leftover prompt after a fingerprint win (known cosmetic quirk of
+      the hack — pthread_cancel'd prompt). `fingerprint.parallel = false`
+      must restore the old sequential behavior. VM already asserts the
+      PAM stack shape + password-only lockout safety with no reader
+      (checks.hardware-toggles).
 - [ ] **#55 fingerprint enroll on real reader** — with
      `nomarchy.hardware.fingerprint.enable` and a physical reader: System ›
      Fingerprint › Enroll a finger; List shows it; Verify succeeds; optional
--- a/agent/JOURNAL.md
+++ b/agent/JOURNAL.md
@@ -19,6 +19,29 @@ Template:

 ---

+## 2026-07-12 — parallel fingerprint-or-password (interactive, promoted)
+- **Task:** Bernardo promoted the PROPOSED "fingerprint or password in
+  parallel" item live; wants it default-on for fingerprint-PAM users.
+- **Did:** Packaged pam-fprint-grosshack v0.3.0 (pkgs/, source-reviewed
+  first: all failure paths → PAM_AUTHINFO_UNAVAIL, typed password only
+  ferried via AUTHTOK to pam_unix try_first_pass — can't lock out
+  password login). New `nomarchy.hardware.fingerprint.parallel`
+  (default true; false = stock sequential). Wiring swaps stock fprintd's
+  rule modulePath (mkForce) so ordering is inherited. README/template
+  rows; BACKLOG PROPOSED entry closed into ROADMAP ✓.
+- **Verified:** V2 — checks.hardware-toggles extended to three nodes and
+  green: parallel node asserts grosshack line before pam_unix in
+  /etc/pam.d/sudo AND `sudo -S` with the right password succeeds /
+  wrong password fails with NO reader present (the lockout invariant);
+  seqpam node = stock pam_fprintd, no grosshack; nopam = neither.
+  Package builds (meson needed libpam-wrapper + python3). flake check
+  green.
+- **Pending:** V3 on the AMD dev box (HARDWARE-QUEUE): the actual
+  type-or-touch race, fprintd-stopped fallback, hyprlock/greeter
+  behavior after a fingerprint win (pthread_cancel'd prompt quirk).
+- **Next suggestion:** dock + fingerprint V3 batch on hardware, then
+  #89 slice 3.
+
 ## 2026-07-12 — undock blackout rescue (interactive follow-up)
 - **Task:** Bernardo: "if I turn the laptop screen off and undock, does
  the panel come back?" Answer had to be tested, not recalled.
--- a/docs/ROADMAP.md
+++ b/docs/ROADMAP.md
@@ -443,6 +443,27 @@ Design/decision records and a running log of shipped work (items marked
  V3 decides if the menu row needs a mirror-based rework. Also fixed in
  the rescue: `grep -c .` exits 1 at count 0 — an `||`-guard on that
  pipeline silently disabled the rescue exactly when it mattered.
+  ✓ **Parallel fingerprint-or-password (2026-07-12, Bernardo promoted
+  from PROPOSED):** `nomarchy.hardware.fingerprint.parallel` (default
+  **true** — the better UX is what opting into fingerprint PAM gets you;
+  `false` restores stock sequential pam_fprintd). Implementation:
+  packaged `pam-fprint-grosshack` v0.3.0 (pkgs/, GitLab pin — the
+  field-standard fprintd fork; stock PAM cannot express parallel
+  factors, linux-pam#301; the cleaner-concept `pam-any` stays the
+  fallback candidate if grosshack fights greetd/hyprlock). Source
+  reviewed before packaging: every failure path returns
+  PAM_AUTHINFO_UNAVAIL (falls through to password) and a typed password
+  is only ferried via PAM_AUTHTOK to the stock
+  `auth sufficient pam_unix.so … try_first_pass` — the hack never
+  validates passwords itself, so password login cannot be locked out by
+  it. Wiring reuses stock fprintd's rule slot (mkForce'd modulePath) so
+  ordering is inherited, not recomputed. checks.hardware-toggles grew to
+  three nodes: parallel default (stack shape + password-works/
+  wrong-password-fails with no reader), parallel=false (stock
+  pam_fprintd), pam=false (neither). Real-reader race → HARDWARE-QUEUE
+  (AMD dev box). Accepted quirks (documented in the package): process-
+  wide SIGUSR1 handler, pthread_cancel'd prompt on fingerprint win,
+  prompt buffer not zeroized.
  ✓ **neon-glass finish (#88, `VISION § D`):** rewrote whole-swap
  `rofi.rasi` to rofi-native `@color` glass panel (cyan rim, soft
  selection wash — same hex-alpha glass pattern as Boreal); btop title/
--- a/flake.nix
+++ b/flake.nix
@@ -93,6 +93,7 @@
        # switch can refresh a broken system-package nomarchy-pull.
        # Includes nomarchy-what-changed (generation readability, #82).
        nomarchy-lifecycle = final.callPackage ./pkgs/nomarchy-lifecycle { };
+        pam-fprint-grosshack = final.callPackage ./pkgs/pam-fprint-grosshack { };
      };

      nixosModules.nomarchy = {
@@ -539,7 +540,11 @@
          # what they SET (kernel cmdline, fprintd, PAM). Real hardware
          # behaviour (firmware/driver/device) needs bare metal and is out of
          # scope here. Imports only hardware.nix, so the VM stays minimal.
-          # Two nodes: pam=true must wire pam_fprintd; pam=false must NOT
+          # Three nodes: pam=true wires the PARALLEL module by default
+          # (pam_fprintd_grosshack in stock fprintd's rule slot, before
+          # pam_unix) and password-only auth must still work with no
+          # reader present — the lockout-safety invariant; parallel=false
+          # wires stock sequential pam_fprintd; pam=false wires neither
          # (NixOS defaults fprintAuth from fprintd.enable — we force off).
          hardware-toggles = pkgs.testers.runNixOSTest {
            name = "nomarchy-hardware-toggles";
@@ -552,6 +557,17 @@
                  fingerprint = { enable = true; pam = true; };
                  npu.enable = true;
                };
+                users.users.alice = {
+                  isNormalUser = true;
+                  password = "t0ps3cret";
+                  extraGroups = [ "wheel" ];
+                };
+              };
+              seqpam = { ... }: {
+                imports = [ ./modules/nixos/hardware.nix ];
+                nomarchy.hardware.fingerprint = {
+                  enable = true; pam = true; parallel = false;
+                };
              };
              nopam = { ... }: {
                imports = [ ./modules/nixos/hardware.nix ];
@@ -564,7 +580,23 @@
              assert "amd_pstate=active" in cmdline, cmdline
              assert "i915.enable_guc=3" in cmdline, cmdline
              machine.succeed("systemctl cat fprintd.service")
-              machine.succeed("grep -q pam_fprintd /etc/pam.d/sudo")
+              machine.succeed("grep -q pam_fprintd_grosshack /etc/pam.d/sudo")
+              # The parallel rule must be an auth line ordered BEFORE
+              # pam_unix — its typed password is only ferried to pam_unix.
+              machine.succeed(
+                "awk '/^auth/ && /pam_fprintd_grosshack/ {g=NR} "
+                "/^auth/ && /pam_unix/ {u=NR} "
+                "END {exit !(g && u && g < u)}' /etc/pam.d/sudo"
+              )
+              # Lockout safety: this VM has no fingerprint reader, so the
+              # grosshack rule can only fail through — the password alone
+              # must still authenticate sudo (and a wrong one must not).
+              machine.succeed("su - alice -c 'echo t0ps3cret | sudo -S -k true'")
+              machine.fail("su - alice -c 'echo wrongpw | sudo -S -k true'")
+
+              seqpam.wait_for_unit("multi-user.target")
+              seqpam.succeed("grep -q pam_fprintd /etc/pam.d/sudo")
+              seqpam.fail("grep -q pam_fprintd_grosshack /etc/pam.d/sudo")

              nopam.wait_for_unit("multi-user.target")
              nopam.succeed("systemctl cat fprintd.service")
--- a/modules/nixos/hardware.nix
+++ b/modules/nixos/hardware.nix
@@ -112,6 +112,20 @@ in
          menu) when set; otherwise false.
        '';
      };
+
+      parallel = lib.mkOption {
+        type = lib.types.bool;
+        default = true;
+        description = ''
+          With fingerprint PAM on, accept the password OR a fingerprint at the
+          same prompt (type or touch, whichever comes first) instead of stock
+          pam_fprintd's sequential wait-for-the-reader-then-password. Uses the
+          pam-fprint-grosshack module (an fprintd fork — source-reviewed; every
+          failure path falls through to the normal password rule, so password
+          login can never be locked out by it). Set false for the stock
+          sequential behavior.
+        '';
+      };
    };

    npu.enable = lib.mkEnableOption ''
@@ -205,7 +219,20 @@ in
        "passwd" "chsh" "chfn" "chpasswd"
        "polkit-1" "swaylock"
        "groupadd" "groupdel" "groupmod" "groupmems"
-      ] (_: { fprintAuth = cfg.fingerprint.pam; });
+      ] (_: {
+        fprintAuth = cfg.fingerprint.pam;
+      } // lib.optionalAttrs (cfg.fingerprint.pam && cfg.fingerprint.parallel) {
+        # Parallel mode: same rule slot as stock fprintd (so ordering —
+        # sufficient, before pam_unix — is inherited), different module.
+        # grosshack prompts for the password itself while polling the
+        # reader; whichever lands first wins. A typed password makes the
+        # rule FAIL with the token stored, and the stock
+        # `auth sufficient pam_unix.so … try_first_pass` right after it
+        # does the actual validation — password stays sufficient on its
+        # own, so a broken reader/fprintd can never lock login out.
+        rules.auth.fprintd.modulePath = lib.mkForce
+          "${pkgs.pam-fprint-grosshack}/lib/security/pam_fprintd_grosshack.so";
+      });
    })

    # ── Newest kernel for very-new hardware (opt-in escape hatch) ──────
--- a/pkgs/pam-fprint-grosshack/default.nix
+++ b/pkgs/pam-fprint-grosshack/default.nix
@@ -0,0 +1,50 @@
+# pam_fprintd_grosshack.so — fprintd's PAM module forked to accept the
+# password OR a fingerprint at the same prompt (upstream calls itself a
+# "gross hack"; it is also the field-standard answer to this PAM gap —
+# stock PAM cannot express parallel factors, linux-pam#301).
+#
+# Source reviewed before packaging (2026-07-12, v0.3.0 = fprintd 1.94.2
+# base + ~60-line delta): every failure path — no reader, no enrolled
+# prints, fprintd absent, timeout, password typed — returns
+# PAM_AUTHINFO_UNAVAIL, i.e. the module FAILS and PAM falls through to
+# the password rule; a typed password is never validated here, only
+# ferried via PAM_AUTHTOK to pam_unix (try_first_pass). Accepted
+# quirks: installs a process-wide SIGUSR1 handler in the calling
+# process, pthread_cancels the prompt thread on fingerprint win, and
+# does not zeroize the prompt buffer. Consumed by
+# modules/nixos/hardware.nix (nomarchy.hardware.fingerprint.parallel).
+{ lib, stdenv, fetchFromGitLab, meson, ninja, pkg-config, gettext, python3
+, glib, libfprint, polkit, pam, systemd, dbus, libpam-wrapper }:
+
+stdenv.mkDerivation rec {
+  pname = "pam-fprint-grosshack";
+  version = "0.3.0";
+
+  src = fetchFromGitLab {
+    owner = "mishakmak";
+    repo  = "pam-fprint-grosshack";
+    rev   = "v${version}";
+    hash  = "sha256-obczZbf/oH4xGaVvp3y3ZyDdYhZnxlCWvL0irgEYIi0=";
+  };
+
+  # Only the PAM module is built (the fork disables every other fprintd
+  # subdir), but the top-level meson still resolves the full fprintd
+  # dependency set — hence libfprint/polkit in buildInputs.
+  # pam_wrapper is only exercised by the (disabled) test suite, but the
+  # top-level meson marks it required whenever the pam option is on.
+  nativeBuildInputs = [ meson ninja pkg-config gettext python3 ];
+  buildInputs       = [ glib libfprint polkit pam systemd dbus libpam-wrapper ];
+
+  mesonFlags = [
+    "-Dpam_modules_dir=${placeholder "out"}/lib/security"
+    "-Dsystemd=false"
+    "-Dman=false"
+  ];
+
+  meta = {
+    description = "PAM module accepting password or fingerprint in parallel (fprintd fork)";
+    homepage    = "https://gitlab.com/mishakmak/pam-fprint-grosshack";
+    license     = lib.licenses.gpl2Plus;
+    platforms   = lib.platforms.linux;
+  };
+}
--- a/templates/downstream/system.nix
+++ b/templates/downstream/system.nix
@@ -63,6 +63,7 @@
  #   amd.rocm.gfxOverride = "11.0.0";          #   HSA override for an unlisted iGPU
  #   fingerprint.enable = true;                #   fprintd; installer-set when a reader is detected
  #   fingerprint.pam = true;                   #   use the fingerprint for login + sudo
+  #   fingerprint.parallel = false;             #   sequential prompt instead of password-or-finger
  #   npu.enable = true;                        #   on-die NPU driver (experimental; userspace runtime BYO)
  #   latestKernel = true;                       #   newest kernel for very-new hardware (drivers not yet in the default)
  #   camera.hideIrSensor = true;               #   dual-sensor webcam: hide the IR node so apps get the color cam